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# Different plate types and their properties

Contents

## Overview

Diamonds contains a lot of plate types. The table below gives an overview of their differences

Icon Which thickness bears one or two direction(s)? Display of stresses Reinforcement zones Examples
principle

x’-direction

secundairy

z’-direction

(e) in two directions

(1) in one direction
(e) – (1) in two directions

(e) in one direction

–
(e) in two directions
the ribs in one direction
(e) in two directions
the ribs in one direction

(3) and (4) in two directions
the ribs in one direction

(3) and (4) in two directions
the ribs in one direction
(e) in one direction reinforcement calculation not possible
this plate type (a membrane) has no bending stiffness, only axial stiffness reinforcement calculation not possible  –
bearing direction is imposed by the user-defined stiffness matrix reinforcement calculation not possible

1. The weight gain due to the holes can be compensated either by applying an up an upward load on the relevant plates or by adjusting the concrete density in the material library for the relevant plates.

## FAQ

There are two options to model a hollow-core-slabs. Which one do I use?

The two options we’re talking about are  and .

• If you only want to take the stiffness into account, use . It will allow you to easily take the weight gain due to the holes into account.
• If you want to view stresses and/or calculate the reinforcement, use .

Besides the above mentioned difference, there is another difference regarding the torsional rigidity (= D66 in the stiffness matrix) :

By default the torsional rigidity is neglected ( = the torsional factor is equal to zero%) to match beam-behaviour.

The user can take the torsional ridigidy into account by entering a value for the torsion factor.

By default the torsional rigidity is calculated using a torsion factor of 80%.

The user cannot change the torsion factor.

If you want both approaches to result in similar results, the torsional rigidity with should be set to 80%. A torsional factor of 80% also matches more the real life behaviour of a slab than 0%.

This plate type  is not suitable for hollow-core-slabs since the upper and lower ‘flenge’ of the plate bear in two directions while a hollow-core-slab has a one-directional behaviour.

Why are the stresses not available for some plate types?
For some plate types, it is difficult to properly display the stresses since the cross section of the plate is not constant over the thickness of the plate.
What does the option 'Crack calculation with reduced height' mean?
This option is only visible when selecting a préslab. Read all about it in this article.
How do I model pre-tensioning or post-tensioning?
It is not possible to model pre- or post-tensioning in our software. Not for beams/columns, not for slabs, plates, walls.
How to model a steeldeck
There is no ready-to-use plate type for a Steeldeck. Usually it is neglected in the stability calculations.
If you do want to take the stiffness somehow into account, you could enter the stiffness matrix. EN 1993-4-1 §4.4 gives a brief explanation for corrugated sheeting. Make sure to apply the correct boundary conditions along the plate borders.
Can I model a plate with a variable thickness?
Diamonds has no automatic function to create slabs/plates with a variable thickness. To approach the variable thickness, you could divide the slabs into small strips giving each strip a different thickness. Make sure the strips don’t get too small.